As the greenhouse environment gets colder, and sunlight becomes sparser, growers need to adjust their climate control methods to address new issues.
These 5 tips will help you maintain ideal greenhouse conditions throughout the cold season, and even save energy in the process.
01. Close the Greenhouse and Use Dehumidifiers
Low temperatures slow down the plants’ metabolic processes. This leads to slower growth, less fruit, and lower quality yields. So, when it’s cold outside, the first thing any grower can do, is close the greenhouse.
Closing greenhouse windows and vents keeps heat inside and protects crops from the cold. You can further insulate your greenhouse by finding and fixing any leaks you may have in the greenhouse cover.
When it’s cold outside, it’s also, in many cases, more humid. This is due to the air’s physical properties – at lower temperatures, it can carry much less water vapor, increasing the relative humidity. So, growers who ventilate in order to release humidity from inside the greenhouse, may find it much less effective during the fall and winter.
Controlling humidity can be much more challenging during these seasons. The only way to ensure, with complete certainty, that relative humidity doesn’t rise to 100%, is to use dehumidification.
By controlling humidity from inside, growers can avoid ventilation, keeping the heat they generate locked inside the greenhouse.
02. Spread Thermal Screens
Another way to improve heat retention in the greenhouse, is to deploy thermal screens. Screens create a buffer between the cold ceiling and the rest of the greenhouse, creating better insulation, and a more manageable greenhouse space.
There’s another issue that’s especially difficult to avoid when it’s cold outside – condensation drips. As the greenhouse roof gets colder, condensation inevitably forms on the ceiling. Thermal screens, acting as a buffer, prevent these drips from reaching the plants. This ultimately helps to prevent some of the most common greenhouse diseases, like gray mold or powdery mildew.
03. Heat Less & Save Energy
Closing the greenhouse windows and vents, and deploying thermal screens, helps retain the heat you generate. It doesn’t matter if you use heating pipes, a heat pump, HVAC, or any other heating system. By retaining heat inside, you can heat much less.
Using a dehumidifier may be critical for this to succeed. Without the proper solution to actively reduce humidity, you’ll inevitably experience humidity spikes. But ventilating in this case will quickly release hot air from the greenhouse, and cold air from outside will replace it, requiring reheating.
Operating in a closed greenhouse with dehumidification is one of the best ways to reduce energy consumption and can save as much as 50% on heating!
04. Take Lighting into Consideration
Besides cold weather, winter time also means shorter days. There are also more cloudy, rainy, or even snowy days in some regions. So overall, sunlight is in much shorter supply.
In order to provide the best conditions for the plants, growers often introduce grow lights to lengthen the day or add extra radiation. Light is crucial for plants to photosynthesize to their best ability, helping them grow larger and healthier.
But there’s a side-effect to this – they transpire much more water. Using grow lights will inevitably increase humidity in the greenhouse. It’s important to take this into account when planning your humidity control protocol and adjust accordingly.
05. Adjust for Longer Nights
Humidity is most problematic between dusk and dawn, making these hours critical for dehumidification. As the nights grow longer, it’s important to make sure to increase your dehumidifiers’ operation time, to cover these periods.
Maintaining optimal climate conditions throughout the afternoon, night, and early morning, stimulates plant growth and contributes to larger, higher quality yields.
Overall, the cold season presents several unique challenges for greenhouses. But with modern technology and growing techniques, there’s no reason for growers, or plants, to suffer during this time of year.